The object of this study is 1) whether statistically and biologically significant differences in IOP occur in subjective dark versus subjective light phases in light-entrained human subjects; and if so, 2) location of the peak and nadir values in relation to the dark and light phases; 3) the goodness of fit of the data to circadian cosinor function tests; 4) whether established CRIOP amplitude parameters for diagnosis of pressure pathology are statistically consistent with the observed results of the proposed study.